Add default adapter options

lib/faraday.rb

@@ -54,6 +54,10 @@ class << self
     #   @return [Symbol] the new default_adapter.
     attr_reader :default_adapter
 
+    # Option for the default_adapter
+    #   @return [Hash] default_adapter options
+    attr_accessor :default_adapter_options
+
     # Documented below, see default_connection
     attr_writer :default_connection
 
@@ -149,4 +153,5 @@ def method_missing(name, *args, &block)
   self.root_path = File.expand_path __dir__
   self.lib_path = File.expand_path 'faraday', __dir__
   self.default_adapter = :net_http
+  self.default_adapter_options = {}
 end

lib/faraday/rack_builder.rb

@@ -73,7 +73,7 @@ def initialize_dup(original)
     def build
       raise_if_locked
       block_given? ? yield(self) : request(:url_encoded)
-      adapter(Faraday.default_adapter) unless @adapter
+      adapter(Faraday.default_adapter, **Faraday.default_adapter_options) unless @adapter
     end
 
     def [](idx)

spec/faraday/rack_builder_spec.rb

@@ -151,6 +151,33 @@ class Banana < Handler
     end
   end
 
+  context 'when adapter is added with named options' do
+    after { Faraday.default_adapter_options = {} }
+    let(:conn) { Faraday::Connection.new {} }
+
+    let(:cat_adapter) do
+      Class.new(Faraday::Adapter) do
+        attr_accessor :name
+
+        def initialize(app, name:)
+          super(app)
+          @name = name
+        end
+      end
+    end
+
+    let(:cat) { subject.adapter.build }
+
+    it 'adds a handler to construct adapter with named options' do
+      Faraday.default_adapter = cat_adapter
+      Faraday.default_adapter_options = { name: 'Chloe' }
+      expect { cat }.to_not output(
+        /warning: Using the last argument as keyword parameters is deprecated/
+      ).to_stderr
+      expect(cat.name).to eq 'Chloe'
+    end
+  end
+
   context 'when middleware is added with named arguments' do
     let(:conn) { Faraday::Connection.new {} }